The present invention relates to an inkjet recording head which uses, as a pressure generating source, piezoelectric vibration elements of the longitudinal vibration type, which are each constructed such that a plurality of internal electrodes are alternately layered in a state that piezoelectric material is interposed therebetween.
The inkjet recording head, which uses the piezoelectric vibration elements each vibrating in the longitudinal vibration mode, includes a plurality of linear arrays each consisting of pressure generating chambers, each chamber communicating with a nozzle orifice and a part of each chamber being sealingly closed with an elastically deformable plate member. Each pressure generating chamber is expanded and contracted by its associated piezoelectric vibration element which axially deflects in accordance with a drive signal applied thereto.
The piezoelectric vibration elements are constructed as a unit form as shown in FIG. 15. That is, a piezoelectric vibrating plate, which is wide enough to cover a plurality of piezoelectric vibration elements, is fastened to a fixing plate 60, and is cut into a plurality of piezoelectric vibration elements 61 with a wire saw or the like to be arranged at a constant pitch.
Dummy piezoelectric vibration elements 62 and 63, which are not associated with the ink drop ejecting operation, are provided at both ends of a linear array of piezoelectric vibration elements in order to improve the workability in positioning the piezoelectric vibration elements in the stage of assembling. In assembling the piezoelectric vibration elements, the outer side surfaces 62xe2x80x2 and 63xe2x80x2 of the dummy piezoelectric vibration elements 62 and 63 are used as a reference in setting the piezoelectric vibration element unit to a case, whereby the piezoelectric vibration elements 61 are positioned with respect to the fluid channel unit within a predetermined tolerance.
The piezoelectric vibrating plate is formed such that internal electrode material layers including metal and piezoelectric material layers are layered, and the resultant layered structure is sintered. The cutting of the thus formed piezoelectric vibrating plate with a wire saw into a plurality of piezoelectric vibration elements will minutely shift the actual cutting lines from the correct cutting lines since the internal electrodes are hard. The shift of the cutting lines greatly affects an accuracy of the relative positioning of the piezoelectric vibration element unit when the distal ends of the piezoelectric vibration elements are reduced in area for the purpose of increasing a print density.
Accordingly, an object of the present invention is to provide an inkjet recording head in which piezoelectric vibration elements are positioned at predetermined positions with high accuracy.
Another object of the invention is to provide a piezoelectric vibration element unit which is configured with high accuracy.
A third object of the invention is to provide a method of manufacturing the piezoelectric vibration element unit.
According to the present invention, a dummy piezoelectric element is disposed at least at one of the ends of a linear array of piezoelectric vibration elements. A region not including an internal electrode is provided in the vicinity of the outer side surface of said dummy piezoelectric vibration element. When the outer side surface of the dummy piezoelectric element is formed by cutting, a shift of a cutting line due to high hardness of the internal electrode is minimized. That is, the outer side surface of the dummy piezoelectric element can be defined with high accuracy. The piezoelectric vibration element unit can be positioned with high accuracy using the dummy piezoelectric element as a positioning reference.
An inkjet recording head according to the present invention preferably includes a piezoelectric vibration element unit in which a plurality of piezoelectric vibration elements, each of which is axially expandable, and is made up of piezoelectric material layers and internal electrodes which are alternately layered, are linearly arrayed on a substrate. The volumes of pressure generating chambers are increased and decreased by said piezoelectric vibration elements associated respectively with said pressure generating chambers. A dummy piezoelectric vibration element is provided at least one end of a linear array of piezoelectric vibration elements, and a region not including the internal electrodes is provided in the vicinity of the outer side surface of said dummy piezoelectric vibration element.
Thus, in the inkjet recording head of the preferable construction, the internal electrodes are not contained in a region in the vicinity of the outer side surface of said dummy piezoelectric vibration element. Therefore, the cutting of the piezoelectric vibrating plate along the outer side surface of the dummy piezoelectric vibration element does not cause a shift of an actual cutting line from the correct cutting line due to the high hardness of the internal electrodes. Therefore, the piezoelectric vibrating plate can be highly accurately cut.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. Hei. 11-85788 (filed on Mar. 29, 1999) and 2000-76269 (filed on Mar. 17, 2000), which are expressly incorporated herein by reference in their entireties.